Connecting pins in the nature of removable coupling devices for joining machinery elements or other apparatus have been known in the art for many years. Such connecting pins are employed for temporarily joining a plurality of machine elements or other members which have attachment apertures to provide a mode of interconnection. Such connecting pins are referred to as pivot pins or a variety of other names, depending upon the particular application involved and terminology which may have evolved in a particular industry.
Classically, such connecting pins extend through the apertures in normally two members for purposes of temporarily joining the members for some type of machine operation where the two machine elements are to operate as a unit. In many such applications, it is necessary to regularly or intermittently decouple the machine elements by removal of the connecting pin. This is necessary, for example, to dismantle the machine elements, replace worn parts, or for other similar reasons.
In a great many applications, it is possible to selectively employ a solid pin to achieve these operational characteristics. Depending upon the particular application, these solid pins may be cylindrical or tapered to facilitate insertion in the attachment apertures of the mating machine elements. Depending upon various considerations such as orientation, load application, and other similar factors, it may be sufficient that such connecting pins are provided with merely a head or collar at one extremity which maintains it in place in the attachment apertures of the particular machine elements. In other instances, it may be necessary to provide the connecting pin with throughbores for receiving cotter pins proximate both extremities thereof, or collects or other fasteners may be employed at one or both ends of the pivot pin to retain the pin in position.
For most applications, it is necessary or desirable that the pin be closely sized to snugly fit in the attachment apertures of the machine elements in order to preclude undesirable movement of the machine elements relative to each other. In applications where a solid connecting pin is only infrequently removed and the machine elements are subject to the outdoors or an otherwise corrosive environment, the pin and/or the attachment apertures of the machine elements may become sufficiently corroded such as to create extreme difficulty in attempting to remove a solid connecting pin.
In many instances, it may be necessary to strike the pin and machine elements in an area in proximity thereto with a hammer or other heavy object to sufficiently free the pin such that it may be removed from the attachment apertures of the machine elements. Not infrequently the pin and/or the machine elements may be damaged merely in the process of effecting removal of the pin in this manner. Although manufacturing the pin and/or the attachment elements of a material that resists corrosion may be possible in some instances, it is not a uniform solution for all applications and can result in excessively expensive parts. While the use of lubricants can be helpful in some circumstances, they are similarly unsatisfactory in all applications and can become essentially ineffectual over an extended time period. Thus, no reliable, inexpensive solution is in use that eliminates the problem of removing solid connecting pins which have become corroded in attachment apertures of machine elements.